This blog provides updated forecasts and comments on current weather or other topics

Wednesday, December 28, 2011

Subtropical Moisture, Record Lost, and Thank You

First, the thank you. I very much appreciate the contributions of over one hundred of you to my weather research fund. It has allowed me to fill in the financial holes for running the local weather prediction modeling research, helping to make up for losses as funding agencies reduce support. Furthermore, I am dedicating $2000 of the support for an undergraduate Weather Research scholarship. As an instructor and the department's undergraduate adviser, I see first hand the impact of the rapidly rising UW tuition, with many of our undergraduates acquiring large debt levels and working more and more hours--leaving less time for study and sleep. The most extreme case of this was one student that kept on falling asleep in my junior synoptics class. I talked to him one day about it...turns out he was supporting himself by fueling jets at Sea-Tac airport overnight! Anyway, as long as the contributions come in I would like to continue using a portion of the funds for scholarships. And thank you to all of you that have sent me tips and suggestions about my lost dog Leah. She is still roaming around Mountlake Terrace and it is maddening that we have not found her yet.

Today, it was warm, moist and balmy---the warmest and wettest day in over a month. Many locations in western Washington reached the mid-50s, as subtropical, southwesterly flow surged into the region. As apparent from this satellite-based vertically integrated water vapor content image, the moisture plume did not come from near Hawaii, but pushed westward and northward across the north-central Pacific (purple and red, highest values, followed by orange and yellow). This is a modest atmospheric river with origins in the subtropics.

The plume most directly intersected the coast south of Washington on the northern Oregon coast, and thus the higher precipitation amounts were to our south. Here is the 24-h precipitation totals ending 9 PM on Wednesday. Values ranged from a trace (.01 inch) in the middle of the rainshadow NE of the Olympics to 3-5 inches on the western slopes of the Olympics, coastal mountains and Cascades, with particularly large amounts over NW Oregon. Talking about rainshadows, amazing low values in eastern Washington (trace to a few hundredths of an inch).

And as long as we are talking rainshadows...here is a radar sample during the early afternoon, when the shadow was centered near Everett. You got to love living around here---you can be completely dry at one location, but pouring a short car drive away.

A weak disturbance comes in later tomorrow (Thursday), a stronger system on Friday, and believe it or not, a relatively dry New Year's weekend is ahead. A very normal situation.

Finally, the rainfall today has prevented Seattle from enjoying the driest December on record---we did have the driest first three weeks on record, though. But the drought and the west coast ridging that produced a mainly dry December has resulted in the western U.S. snowpack being well below normal. Here is the latest snow water equivalent chart, giving the % of normal. Washington is now mostly 70-100% of normal, Oregon about 50% of normal, and the CA Sierras down under 20%. Want above-normal snow? Head to Arizona and New Mexico!

13 comments:

Looking at the temp at the house yesterday (the 27th), the low was at the 12:01a and the temperature rose for a full 24 hours to end at a high at 11:59p. Not sure I have ever seen a day here were the temperature only went up from one measurement to the next.

Went out side about 4:30a and it was amazingly warm. Somewhere around 51F.

It was clear all night last night and with daybreak the clouds moved back in. It seems that in winter we often have more clear spells at night than during the day. Is it my imagination or is there a diurnal cycle to the weather fronts?

Saw something interesting on the radar today, probably only discernable offshore thanks to the langley radar. I was watching the front come in on the pac nw regional radar loop (from uw atmos page) and I noticed, for the first time ever, what looked like lower-level showers moving in a northwest direction underneath the main precip sheild that was moving in a northeast direction. The time period was just before noon PST. Mainly visible just off of Ocean Shores.

A spectacular cloudburst rumbled across the Key Peninsula at about 0300. It stared suddenly with a very long, deep rumbling thunder followed by swirling and very dynamic and forceful wind bursts along with sideways hail. The whole event lasted only a few minutes. It was the most intense squall I've seen in a long time. The image of an angry cartoon cloud rolling across the landscape comes to mind. Any reports of this event?

Cliff, sorry if this is a double post, but Google is currently blocking your progress to post by compelling you to give them your cell number, and I don't have one.

Cliff, I'm surprised that you haven't written about how nicely your department composite radar loop combines the ATX and LGX data. Right now (1420 to 1505 PST 30th), the precip bands are coming from the WNW, you see Mt. Oly peak events, then a PERFECTLY CLEAR circle which encompasses Tacoma. Absolutely textbook rain shadowing by the Olympics. So perfectly formed that you would think it was faked. Seeing this would have never been possible before LGX came on line and your department added it to your composite loop. Great work in promoting both of them!

I made an animation using NCDC century values for both temp and precip, for the 10 'climate divisions' of Washington. The temperature animation doesn't reveal any particular pattern to my eyes, but the precip animation shows the dynamic aspect of the Cascade rain shadow dramatically. Nina and Nino years alternate, causing big differences in wetness on the west side, while the eastern zones remain nearly constant over the years.

Many Years ago doing astonomy on a side road near Paradise it was t-shirt warm all night in April; piles of snow all around me. I could never figure out what happened that night until your Heatwave Blogs. I always wondered if my memory was playing me false. Many Thanks.